Mobile home dwellers say a proposed state law requiring septic tank, sewer and water inspections at parks where their homes are located is desperately needed while owners of those parks say it could put them out of business.

Just the septic tank inspections could cost $300 to $500 for each tank, said Mark Asnes, who owns 11 mobile home parks in Massachusetts and Connecticut, including two in Westfield: Riverbend on Springfield Road and Oaks Southwick Road. Water inspections could cost almost as much.

“That might be half your profit for the year,” said Asnes, a vice president of the Massachusetts Manufactured Housing Association for the western part of the state. “There is always going to be good landlords and bad landlords

“It creates hardship. At the end of the day, we own businesses,” Asnes said. “The costs have to be passed down to the resident.”

He said he’s already regulated by local boards of health.

But mobile home park resident Jesse Martinez, who is also president of the statewide residents group Manufactured Home Federation of Massachusetts, said some parks are plagued with poor water or inadequate pressure. In some cases, existing laws end where the city water pipe enters the property.

Martinez said Massachusetts has 252 mobile home park communities with 65,000 residents total.

“There isn’t as much regulation once it splits off from there,” he said. “A lot of people move into these parks on faith. They think it looks good, so they go ahead and move in.”

But once there, Martinez said, mobile home owners might be stuck They own their homes but not the lots under them. Many are low- to moderate income and can’t afford the $5,000 to $8,000 it would cost to move their home to a new park.

“That’s if they could be moved at all,” he said. “You are invested in these communities, but there are a lot of health and safety issues at some of them.”

Martinez and his neighbors at Wheel Estates in North Adams banded together last month and bought their park and made it into a cooperative. The residents will invest just more than $1 million in road, water and sewer improvements.

Asnes said he’s invested more than $300,000 to upgrade the septic systems at each of his two Westfield parks since buying them in 2008 and 2011. He recently purchased a park in the town of Wales.

Massachusetts Attorney General Martha Coakley supports the proposed certificate program, saying it would replace the current system of enforcement and litigation. The state Attorney General's Office is called upon often to handle mobile home park disputes [pdf], according to a news release.

Martinez said the proposed law, which is now in committee, also includes a means of settling disputes outside of court.

“That would save both the parks and the residents money,” he said. “We need to keep people out of court.”